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Effects of Two Kinds of Heavy Metals Including Cr^(6+) and Pb^(2+) on Garlic Germination 被引量:3
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作者 柯佳颖 吴文杰 陈细香 《Agricultural Science & Technology》 CAS 2011年第2期171-174,共4页
[Objective] This study aimed to revealing the effects of two kinds of heavy metals including Cr6+ and Pb2+ on garlic germination.[Method] Root length,enzyme(SOD and CAT)activity and soluble protein content during ... [Objective] This study aimed to revealing the effects of two kinds of heavy metals including Cr6+ and Pb2+ on garlic germination.[Method] Root length,enzyme(SOD and CAT)activity and soluble protein content during garlic germination were determined under the stress of two kinds of heavy metals including Cr6+ and Pb2+.[Result] During garlic germination,there was an obvious inhibition on buds and seedlings when the concentration of heavy metals including Cr6+ and Pb2+ was more than 20 mg/L,while SOD and CAT had certain buffering ability to the heavy metal toxicity with low concentration.With the stress of Cr6+ in low concentration,SOD activity increased with the increase of metal ion concentration,and then reached maximum when the treatment concentration was 50 mg/L,while CAT activity gradually increased when Cr6+ concentration was lower than 20 mg/L.With the high concentration of Cr6+(more than 50 mg/L)or the Pb2+ stress,SOD and CAT activity continued to decrease with the increase of concentration of heavy metal ions.With various concentrations of heavy metal(Cr6+ and Pb2+)solution,soluble protein content showed the decreasing trend with time prolong,and the decreasing trend was obvious with the increase of concentration.Moreover,the tolerance of garlic on Cr6+ toxicity was much higher than that on Pb2+.[Conclusion] Two kinds of heavy metals including Cr6+ and Pb2+ have impacts on four factors mentioned above during garlic germination,and this study provides a theoretical basis for further discussion of the toxic mechanism of heavy metals on plants. 展开更多
关键词 GARLIC SOD CAT Soluble protein
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Three-dimensional tensor controlled-source electromagnetic modeling based on the vector finite-element method 被引量:8
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作者 胡英才 李桐林 +2 位作者 范翠松 王大勇 李建平 《Applied Geophysics》 SCIE CSCD 2015年第1期35-46,121,共13页
Scalar CSAMT is only suitable for measurements in one and two dimensions perpendicular to geological structures. For complex 3D geoelectric structure, tensor CSAMT is more suitable. In this paper, we discuss 3D tensor... Scalar CSAMT is only suitable for measurements in one and two dimensions perpendicular to geological structures. For complex 3D geoelectric structure, tensor CSAMT is more suitable. In this paper, we discuss 3D tensor CSAMT forward modeling using the vector finite-element method. To verify the feasibility of the algorithm, we calculate the electric field, magnetic field, and tensor impedance of the 3D CSAMT far-zone field in layered media and compare them with theoretical solutions. In addition, a three-dimensional anomaly in half-space is also simulated, and the response characteristics of the impedance tensor and the apparent resistivity and impedance phase are analyzed. The results suggest that the vector finite-element method produces high-precision electromagnetic field and impedance tensor data, satisfies the electric field discontinuity, and does not require divergence correction using the vector finite-element method. 展开更多
关键词 CSAMT MODEL impedance tensor VFEM
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Accelerating SAGE algorithm in PET image reconstruction by rescaled block-iterative method 被引量:1
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作者 朱宏擎 舒华忠 +1 位作者 周健 罗立民 《Journal of Southeast University(English Edition)》 EI CAS 2005年第2期207-210,共4页
A new method to accelerate the convergent rate of the space-alternatinggeneralized expectation-maximization (SAGE) algorithm is proposed. The new rescaled block-iterativeSAGE (RBI-SAGE) algorithm combines the RBI algo... A new method to accelerate the convergent rate of the space-alternatinggeneralized expectation-maximization (SAGE) algorithm is proposed. The new rescaled block-iterativeSAGE (RBI-SAGE) algorithm combines the RBI algorithm with the SAGE algorithm for PET imagereconstruction. In the new approach, the projection data is partitioned into disjoint blocks; eachiteration step involves only one of these blocks. SAGE updates the parameters sequentially in eachblock. In experiments, the RBI-SAGE algorithm and classical SAGE algorithm are compared in theapplication on positron emission tomography (PET) image reconstruction. Simulation results show thatRBI-SAGE has better performance than SAGE in both convergence and image quality. 展开更多
关键词 positron emission tomography space-alternating generalizedexpectation-maximization image reconstruction rescaled block-iterative maximum likelihood
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Single-Stage Wide-Range CMOS VGA with Temperature Compensation and Linear-in-dB Gain Control 被引量:1
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作者 恽廷华 尹莉 +1 位作者 吴建辉 时龙兴 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2007年第4期518-525,共8页
A novel wide-range CMOS variable gain amplifier (VGA) topology is presented. The proposed VGA is composed of a variable transconductor and a novel variable output resistor and can offer a high gain variation range o... A novel wide-range CMOS variable gain amplifier (VGA) topology is presented. The proposed VGA is composed of a variable transconductor and a novel variable output resistor and can offer a high gain variation range of 80dB while using a single variable-gain stage. Temperature-compensation and decibel-linear gain characteristic are achieved by using a control circuit that provides a gain error lower than ±1.5dB over the full temperature and gain ranges. Realized in 0.25μm CMOS technology, a prototype of the proposed VGA provides a total gain range of 64.5dB with 55.6dB-linear range,a P-1dB varying from - 17.5 to 11.5dBm,and a 3dB-bandwith varying from 65 to 860MHz while dissipating 16.5mW from a 2.5V supply voltage. 展开更多
关键词 linear-in-dB temperature compensation variable-gain amplifier automatic gain control
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《可洪音义》与大型字典编纂 被引量:3
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作者 韩小荆 《古汉语研究》 CSSCI 北大核心 2007年第3期63-66,共4页
《可洪音义》是一部辨析手写佛经中的俗讹难字的大型佛经音义,本文以《汉语大字典》、《中华字海》为例,从订补已有训释、考释疑难僻字等七个方面举例说明其对大型字典编纂的作用。
关键词 《可洪音义》 《汉语大字典》 《中华字海》
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APPLICATION AND IMPLEMENTATION OF REAL-TIME IMAGE ZOOMING WITH THE WALSH TECHNIQUE
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作者 江洁 郁道银 《Transactions of Tianjin University》 EI CAS 2001年第4期229-232,共4页
Based on the study of Walsh transformation,the zooming template of a two dimensional superimposure filter is decomposed and simplified,and it is real time implemented with FPGA.This method is simple and effective.Th... Based on the study of Walsh transformation,the zooming template of a two dimensional superimposure filter is decomposed and simplified,and it is real time implemented with FPGA.This method is simple and effective.The quality of the image is very good. 展开更多
关键词 image zooming two dimensional superimposure filter field programmable gate array (FPGA)
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A signal-summing programmable gain amplifier employing binary-weighted switching and constant-g--_m bias
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作者 马力 王志功 徐建 《Journal of Southeast University(English Edition)》 EI CAS 2017年第2期134-139,共6页
A novel programmable gain amplifier( PGA) based on a signal-summing topology is proposed. Different from conventional signal-summing variable gain amplifiers( VGA),a binary-weighted switching technique is employed... A novel programmable gain amplifier( PGA) based on a signal-summing topology is proposed. Different from conventional signal-summing variable gain amplifiers( VGA),a binary-weighted switching technique is employed to vary the current-steering transistors' aspect ratio to change their transconductance, and hence, an accurate gain step size of 6dB is achieved. The constant-g_m biasing technique and the matching of the transistors and resistors ensures that the gain of the proposed topology is independent of the variation of process, voltage and temperature( PVT). P-well NMOS( Nmetal oxide semiconductor) transistors are utilized to eliminate the influence of back-gate effect which will induce gain error.The source-degeneration technique ensures good linearity performance at a low gain. The proposed PGA is fabricated in a0.18 μm CMOS( complementary metal oxide semiconductor)process. The measurement results show a variable gain ranging from 0 to24 dB with a step size of 6 dB and a maximum gain error of 0. 3dB. A constant 3dB bandwidth of 210 MHz is achieved at different gain settings. The measured output 3rd intercept point(OIP3) and minimum noise figure( NF) are20. 9 dBm and 11.1 dB, respectively. The whole PGA has a compact layout of 0.068 mm^2. The total power consumption is4. 8 mW under a 1. 8 V supply voltage. 展开更多
关键词 programmable gain amplifier variable gain amplifier signal-summing topology constant-gm
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Dam-break Flood Simulation under Various Likely Scenarios and Mapping Using GIS:Case of a Proposed Dam on River Yamuna,India 被引量:6
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作者 Mahendra S.LODHI Devendra K.AGRAWAL 《Journal of Mountain Science》 SCIE CSCD 2012年第2期214-220,共7页
The precision modeling of dam break floods can lead to formulation of proper emergency action plan to minimize flood impacts within the economic lifetime of the assets.Application of GIS techniques in integration with... The precision modeling of dam break floods can lead to formulation of proper emergency action plan to minimize flood impacts within the economic lifetime of the assets.Application of GIS techniques in integration with hydrological modeling for mapping of the flood inundated areas can play a momentous role in further minimizing the risk and likely damages.In the present study,dam break analysis using DAMBRK model was performed under various likely scenarios.Probable Maximum Flood (PMF)calculated for a return period of 1000 years using deterministic approach was adopted for dam break analysis of the proposed dam under various combinations of breach dimensions.The available downstream river cross-sections data sets were used as input in the model to generate the downstream flood profile.Dam break flow depths generated by the DAMBRK model under various combinations of structural failure are subsequently plotted on Digital Elevation Model(DEM)of the downstream of dam site to map the likely affected area.The simulation results reveals that in one particular case the flood without dam may be more intense if a rainfall of significant intensity takes place. 展开更多
关键词 Dam break analysis DAMBRK GIS Flood mapping HYDROPOWER INDIA
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Single channel blind source separation based on ICA feature extraction 被引量:2
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作者 孔薇 杨斌 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2007年第4期518-523,共6页
A new technique is proposed to solve the blind source separation (BSS) given only a single channel observation. The basis functions and the density of the coefficients of source signals learned by ICA are used as the ... A new technique is proposed to solve the blind source separation (BSS) given only a single channel observation. The basis functions and the density of the coefficients of source signals learned by ICA are used as the prior knowledge. Based on the learned prior information the learning rules of single channel BSS are presented by maximizing the joint log likelihood of the mixed sources to obtain source signals from single observation, in which the posterior density of the given measurements is maximized. The experimental results exhibit a successful separation performance for mixtures of speech and music signals. 展开更多
关键词 blind source separation (BSS) independent component analysis (ICA) single channel maximum likelihood
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Soluble ST2:A new and promising activity marker in ulcerative colitis 被引量:8
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作者 David Díaz-Jiménez Lucía E Núez +6 位作者 Caroll J Beltrán Enzo Candia Cristóbal Suazo Manuel varez-Lobos María-Julieta González Marcela A Hermoso Rodrigo Quera 《World Journal of Gastroenterology》 SCIE CAS CSCD 2011年第17期2181-2190,共10页
AIM:To correlate circulating soluble ST2(sST2) levels with the severity of ulcerative colitis(UC) and serum levels of pro-inflammatory cytokines,and to demonstrate the predictive power of sST2 levels for differentiati... AIM:To correlate circulating soluble ST2(sST2) levels with the severity of ulcerative colitis(UC) and serum levels of pro-inflammatory cytokines,and to demonstrate the predictive power of sST2 levels for differentiation between active and inactive UC.METHODS:We recruited 153 patients:82 with UC,26 with Crohn's disease(CD) and 43 disease controls [non-inflammatory bowel disease(IBD)].Subjects were excluded if they had diagnosis of asthma,autoimmune diseases or hypertension.The serum levels of sST2 and pro-inflammatory cytokines [pg/mL;median(25th-75th)] as well as clinical features,endoscopic and histological features,were subjected to analyses.The sST2 performance for discrimination between active and inactive UC,non-IBD and healthy controls(HC) was determined with regard to sensitivity and specificity,and Spearman's rank correlation coefficient(r).To validate the method,the area under the curve(AUC) of receiver-operator characteristic(ROC) was determined(AUC,95% CI) and the total ST2 content of the colonic mucosa in UC patients was correlated with circulating levels of sST2.RESULTS:The serum sST2 value was significantly higher in patients with active [235.80(90.65-367.90) pg/mL] rather than inactive UC [33.19(20.04-65.32) pg/mL],based on clinical,endoscopic and histopathological characteristics,as well as compared with non-IBD and HC(P < 0.001).The median level of sST2 in CD patients was 54.17(35.02-122.0) pg/mL,significantly higher than that of the HC group only(P < 0.01).The cutoff was set at 74.87 pg/mL to compare active with inactive UC in a multicenter cohort of patients.Values of sensitivity,specificity,and ability to correctly classify UC,according to activity,were 83.33%,83.33% and 83.33%,respectively.The AUC of the ROC curve to assess the ability of this molecule to discriminate between active vs inactive UC was 0.92(0.86-0.97,P < 0.0001).The serum levels of sST2 in patients with UC significantly correlated with endoscopic and histo-pathological scores(r = 0.76 and r = 0.67,P < 0.0001,respectively),and with the pro-inflammatory cytokine,tumor necrosis factor-α(r = 0.69 and r = 0.61,respectively,P < 0.0001).Interestingly,we found a direct correlation between total intestinal ST2 content and serum levels of sST2,adjusted to endoscopic activity score in patients with mild(r = 0.44,P = 0.004),moderate(r = 0.59,P = 0.002) and severe disease(r = 0.82,P = 0.002).Only patients with inactive UC showed no significant correlation(r = 0.45,P = 0.267).CONCLUSION:sST2 levels correlated with disease severity and inflammatory cytokines,are able to differentiate active from inactive UC and might have a role as a biomarker. 展开更多
关键词 Inflammatory bowel disease Ulcerative colitis Soluble ST2 Biomarkers
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Linkage between the Atlantic Tropical Hurricane Frequency and the Antarctic Oscillation in the Western Hemisphere 被引量:6
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作者 FAN Ke 《Atmospheric and Oceanic Science Letters》 2009年第3期159-164,共6页
To examine the zonal asymmetry of the Antarctic oscillation (AAO), different portions of the AAO from June to October (JJASO) in the interannual variability of the Atlantic tropical hurricanes number (ATHN) are docume... To examine the zonal asymmetry of the Antarctic oscillation (AAO), different portions of the AAO from June to October (JJASO) in the interannual variability of the Atlantic tropical hurricanes number (ATHN) are documented in this research. It follows that the AAO in the Western Hemisphere (AAOWH) is positively correlated with the ATHN, at 0.36 during the period of 1871-1998 and 0.42 during the period of 1949-98. After removing the linear regressions on the Southern Oscillation Index (SOI) in all time series, the above correlation coefficients are 0.25 and 0.30, respectively. The underlying mechanisms are studied through analyses of the atmospheric general circulation variability associated with the AAOWH. It turns out that the positive (negative) phase of JJASO AAOWH corresponds with several factors: decreased (increased) vertical zonal wind shear magnitude, low-level anomalous convergence (divergence), high-level anomalous divergence (convergence), and warmed (cooled) sea surface temperature in the tropical Atlantic. Therefore, the positive (negative) phase of JJASO AAOWH is favorable (unfavorable) to the tropical hurricane genesis. 展开更多
关键词 Atlantic hurricanes Antarctic Oscillation in Western Hemisphere Atmospheric Circulation
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Marine Structures: Future Trends and the Role of Universities 被引量:3
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作者 Preben Terndrup Pedersen 《Engineering》 SCIE EI 2015年第1期131-138,共8页
This paper emphasizes some of the challenges and trends associated with the future development of marine structures. Its main focus is on ways to improve the efficiency of energy-consuming ships, and on design challen... This paper emphasizes some of the challenges and trends associated with the future development of marine structures. Its main focus is on ways to improve the efficiency of energy-consuming ships, and on design challenges related to energy-producing offshore structures. This paper also discusses the analysis tools that are most needed to enable sustainable designs for future ships and offshore structures. The last section of the paper contains thoughts on the role of universities in education, research, and innovation regarding marine structures. It discusses curriculum requirements for maritime-technology education, basic research activities, and international cooperation. 展开更多
关键词 marine structures SHIPS offshore structures CURRICULUM researchactivities
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Urban Green Space, Uneven Development and Accessibility: A Case of Dalian′s Xigang District 被引量:3
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作者 YANG Jun LI Chuang +3 位作者 LI Yuechen XI Jianhao GE Quansheng LI Xueming 《Chinese Geographical Science》 SCIE CSCD 2015年第5期644-656,共13页
This study examines the socio-spatial context of uneven development and the residential accessibility of green space in Dalian of Liaoning Province, China. The social fairness was analyzed with a community scale as th... This study examines the socio-spatial context of uneven development and the residential accessibility of green space in Dalian of Liaoning Province, China. The social fairness was analyzed with a community scale as the basis. We combined social scientific methods with a GIS method using a behavior accessibility model from the perspectives of fairness of urban green space allocation based on social geography, geographic information science, management science and many other related discipline theories. The results show that: 1) Most of the urban green space distribution presents an unbalanced phenomenon, and it does not match with the population distribution; 2) We found some differences in the accessibility of the population with different attributes and opportunities to use and enjoy the urban green spaces, mainly due to: the dual social and spatial attributes of the residents and the serious stratum differentiation generated were the internal causes; the residential space differentiation and the pursuit of economic and real estate development were the direct causes; and unreasonable planning, in regard to the fact that government policies did not give consideration to efficiency and fairness, was also an important factor. 展开更多
关键词 behavior accessibility fairness of green space behavior accessibility model Xigang District of Dalian GIS
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Chemical compositions and source apportionment of atmospheric PM_(10) in suburban area of Changsha, China 被引量:2
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作者 李剑东 邓启红 +1 位作者 路婵 黄柏良 《Journal of Central South University》 SCIE EI CAS 2010年第3期509-515,共7页
Source apportionment of particulate matters with aerodynamic diameter less than 10 μm (PM10) was conducted in the suburban area of Changsha, China. PM10 samples for 24 h collected with TEOM 1400a and ACCU system in... Source apportionment of particulate matters with aerodynamic diameter less than 10 μm (PM10) was conducted in the suburban area of Changsha, China. PM10 samples for 24 h collected with TEOM 1400a and ACCU system in July and October 2008 were chemically analyzed by the wavelength dispersive X-ray fluorescence (WD-XRF). Source appointment was implemented by the principal component analysis/absolute principal component analysis (PCA/APCA) to identify the possible sources and to quantify the contributions of the sources to PM10. Results show that as the PM10 concentration is increased from (85.6±43.7) μg/m3 in July 2008 to (107.6±35.7) μg/m^3 in October 2008, the concentrations of the anthropogenic elements (P, S, C1, K, Mn, Ni, Cu, Zn, and Pb) are basically increased but concentrations of the natural elements (Na, Mg, Al, Si, Ca, Ti, and Fe) are essentially decreased. Six main sources of PM10 are identified in the suburban of Changsha, China: soil dust, secondary aerosols, domestic oil combustion, waste incineration, traffic emission, and industrial emission contribute 57.7%, 24.0%, 9.8%, 5.0%, 2.0%, and 1.5%, respectively. Soil dust and secondary aerosols are the two major sources of particulate air pollution in suburban area of Changsha, China, so effective measures should be taken to control these two particulate pollutants. 展开更多
关键词 particulate matters PM10 chemical composition receptor modeling principal component analysis suburban particulate matters PM10 chemical composition receptor modeling principal component analysis SUBURBAN
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Large-Scale Synthesis of Porous Bi2O3 with Oxygen Vacancies for Efficient Photodegradation of Methylene Blue 被引量:2
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作者 Li-rong Wang Ting-ting Hou +5 位作者 Yue Xin Wen-kun Zhu Shu-yi Yu Zi-cheng Xie Shu-quan Liang Liang-bing Wang 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2020年第4期500-506,I0002,共8页
Photocatalytic degradation of organic pollutants has become a hot research topic because of its low energy consumption and environmental-friendly characteristics.Bismuth oxide(Bi2O3)nanocrystals with a bandgap ranging... Photocatalytic degradation of organic pollutants has become a hot research topic because of its low energy consumption and environmental-friendly characteristics.Bismuth oxide(Bi2O3)nanocrystals with a bandgap ranging from 2.0 eV to 2.8 eV have attracted increasing attention due to high activity of photodegradation of organic pollutants by utilizing visible light.Though several methods have been developed to prepare Bi2O3-based semiconductor materials over recent years,it is still difficult to prepare highly active Bi2O3 catalysts in large scale with a simple method.Therefore,developing simple and feasible methods for the preparation of Bi2O3 nanocrystals in large scale is important for the potential applications in industrial wastewater treatment.In this work,we successfully prepared porous Bi2O3 in large scale via etching commercial Bi Sn powders,followed by thermal treatment with air.The acquired porous Bi2O3 exhibited excellent activity and stability in photocatalytic degradation of methylene blue.Further investigation of the mechanism witnessed that the suitable band structure of porous Bi2O3 allowed the generation of reactive oxygen species,such as O2^-·and·OH,which effectively degraded MB. 展开更多
关键词 Bi2O3 photocatalyst Photocatalytic degradation Large scale Visible light PHOTOCATALYSIS
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In-situ synchrotron X-ray diffraction investigation on deformation behavior of Nb/NiTi composite during pre-straining process 被引量:1
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作者 Shun GUO Hui-hui ZHANG +6 位作者 Min-kyung KWAK Wang DING Guang-lei LIU Wen MA Hai-xia LIU Qing-kun MENG Xin-qing ZHAO 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2022年第8期2609-2619,共11页
The mechanisms responsible for deformation behavior in Nb/NiTi composite during pre-straining were investigated systematically using in-situ synchrotron X-ray diffraction, transmission electron microscopy and tensile ... The mechanisms responsible for deformation behavior in Nb/NiTi composite during pre-straining were investigated systematically using in-situ synchrotron X-ray diffraction, transmission electron microscopy and tensile test. It is shown that upon loading, the composite experiences elastic elongation and slight plastic deformation of B19′,B2 and β-Nb phases, together with the forward stress-induced martensitic(SIM) transformation from B2 to B19′. Upon unloading, the deformation mechanisms of the composite mainly involve elastic recovery of B19′, B2 and β-Nb phases,compression deformation of β-Nb phase and incomplete B19′→B2 reverse SIM transformation. In the tensile loading-unloading procedure, besides the inherent elastic deformation and SIM transformation, the(001) compound twins in B19′ martensite can also be conducive to the elastic deformation occurring in B19′-phase of the composite.Therefore, this composite can exhibit a large recoverable strain after unloading owing to the elastic deformation, and the partially reversible and consecutive SIM transformation together with the(001) compound twins. 展开更多
关键词 Nb/NiTi composite near-linear deformation behavior large recoverable strain martensitic transformation
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Correlation between Atmospheric Water Vapor and Diurnal Temperature Range over China 被引量:1
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作者 ZHAO Tian-Bao 《Atmospheric and Oceanic Science Letters》 CSCD 2014年第4期369-375,共7页
Diurnal temperature range (DTR) is an im- portant measure in studies of climate change and variability. The changes of DTR in different regions are affected by many different factors. In this study, the degree of co... Diurnal temperature range (DTR) is an im- portant measure in studies of climate change and variability. The changes of DTR in different regions are affected by many different factors. In this study, the degree of correlation between the DTR and atmospheric precipitable water (PW) over China is explored using newly homogenized surface weather and sounding observations. The results show that PW changes broadly reflect the geographic patterns of DTR long-term trends over most of China during the period 1970-2012, with significant anticorrelations of trend patterns between the DTR and PW, especially over those regions with higher magnitude DTR trends. PW can largely explain about 40% or more (re 0.40) of the DTR changes, with a d(PW)/d(DTR) slope of -2% to -10% K^-1 over most of northwestern and southeastern China, despite certain seasonal dependencies. For China as whole, the significant anticorrelations between the DTR and PW anomalies range from -0.42 to -0.75, with a d(PW)/d(DTR) slope of-6% to -11% K^-1. This implies that long-term DTR changes are likely to be associated with opposite PW changes, approximately following the Clausius-Clapeyron equation. Furthermore, the relationship is more significant in the warm season than in the cold season. Thus, it is possible that PW can be considered as one potential factor when exploring long-term DTR changes over China. It should be noted that the present study has a largely statistical focus and that the underlying physical processes should therefore be examined in future work. 展开更多
关键词 atmospheric water vapor precipitable water diurnal temperature range anticorrelation China
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A Low-Voltage,Low-Power CMOS High Dynamic Range dB-Linear VGA for Super Heterodyne Receivers 被引量:3
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作者 董桥 耿莉 邵志标 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2007年第11期1690-1695,共6页
This paper presents a low-voltage low-power variable gain amplifier,which is applied in the automatic gain control loop of a super heterodyne receiver. Six stages are cascaded to provide an 81dB digitally controlled g... This paper presents a low-voltage low-power variable gain amplifier,which is applied in the automatic gain control loop of a super heterodyne receiver. Six stages are cascaded to provide an 81dB digitally controlled gain range in a 3dB step. The gain step error is less than 0.5dB. It operates at an intermediate frequency of 300kHz, and the power consumption is 1.35mW from a 1.8V supply. The prototype chip is implemented in a TSMC's 0.18μm 1P6M CMOS process and occupies approximately 0.24mm^2 . It is very suitable for portable wire- less communication systems. The measurement results agree well with the system requirements. 展开更多
关键词 variable gain amplifier low voltage low power super heterodyne receiver CMOS RF integratedcircuits
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Response of North Pacific and North Atlantic decadal variability to weak global warming 被引量:5
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作者 WU Sheng LIU Zheng-Yu +1 位作者 CHENG Jun LI Chun 《Advances in Climate Change Research》 SCIE CSCD 2018年第2期95-101,共7页
The Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Variability (AMV) are the two dominant low-frequency modes in the climate system. This research focused on the response of these two modes under ... The Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Variability (AMV) are the two dominant low-frequency modes in the climate system. This research focused on the response of these two modes under weak global warming. Observational data were derived from the Hadley Center Sea Ice and Sea Surface Temperature dataset (HadISST) and coupled model outputs from the Coupled Model Intercomparison Project Phase 5 (CMIP5). Changes in PDO and AMV were examined using four models (bcc-csml-1, CCSM4, IPSL-CM5A-LR, and MPI- ESM-LR) with long weak global warming scenarios (RCP2.6). These models captured the two low-frequency modes in both pre-industrial run and RCP2.6 run. Under weak global warming, the time scales of PDO and AMV significantly decreased while the amplitude only slightly decreased. Interestingly, the standard deviation of the North Pacific sea surface temperature anomaly (SSTA) decreased only in decadal time scale, and that of the North Atlantic SSTA decreased both in interannual and decadal time scales. The coupled system consists of a slow ocean component, which has a decadal time scale, and a fast atmospheric component, which is calculated by subtracting the decadal from the total. Results suggest that under global warming, PDO change is dominated by ocean dynamics, and AMV change is dominated by ocean dynamics and stochastic atmosphere forcing. 展开更多
关键词 Pacific decadal oscillation Atlantic multidecadal variability RCP2.6
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《可洪音义》与疑难俗字考辨
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作者 韩小荆 《励耘语言学刊》 2005年第2期68-83,共16页
本文主要利用《可洪音义》作为依据对《汉语大字典》和《中华字海》中的三十来个疑难俗字进行了考辨,并纠正了旧辞书注释方面的一些错误。
关键词 《可洪音义》 《汉语大字典》 《中华字海》 疑难俗字
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